If their complaint goes to court, it will become a test case at a time when employers are trying to close gender wage gaps. JWT has one of the most unequal salary structures in the advertising industry, according to data released under government rules. The unidentified executives are understood to have gone to their HR department with concerns about how the drive for diversity would affect their career prospects.

Miss Wallace is founder of Good Girls Eat Dinner, a series of networking events which describes itself as providing ‘inspirational, kick-ass female role models across the creative industries (where they are sadly lacking)’. She has described JWT’s poor performance in the gender pay league as a much-needed ‘rocket’ to address the lack of diversity among senior staff.

After the pay gap figures were published JWT implemented a plan to increase diversity through methods such as ‘unconscious bias training for staff’ and a ‘blind recruitment policy’ which would see details such as gender removed from job applications.